Mixed salt lubricant compositions having improved base oils



3,033,787 MIXED SALT LUBRICANT COMPOSITIONS HAVING IMPROVED BASE OILS Arnold J. Morway, Clark, N.J., and Cloyce R. Daniels,

Bethel Park, Pa., assignors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Filed Aug. 11, 1959, Ser. No. 832,922

2 Claims. (Cl. 252-39) This invention relates to lubricating oil compositions containing mixed-salt thickeners and having an improved base oil. Particularly, the invention relates to nixed-salt lubricants in which the baseoil comprises a mixture ofa naphthenic lubricating oil, a solvent extract obtained by solvent extraction of a mineral lubricating oil, and propane precipitated resin. This base oil gives good adhesivea ness and improves the water and fire resistance of the lubricant. V

Recently, lubricating compositions thickened with the calcium salts of low molecular weight fatty acid in combination with calcium salts of higher molecular weight fatty acid have found widespread use in commercial applications. These mixed-salt lubricants have good antiwear and load-carrying ability, which properties made them commercially successful. The commercial versions of these lubricants have been previously prepared with naphthenic mineral lubricating oil having a low viscosity index, which is a common base oil in the lubricants industry. It has now been found that by preparing mixedsalt lubricants with a high viscosity base stock comprising ice dex that the greases tend to thinexcessively at higher temperatures or to excessively harden at low temperatures. However, in the fluid lubricants where V1. is not so important, a combination of naphthenic distillate and solvent extract may be used.

The base oil of the invention will comprise about 60 to 80 wt. percent of naphthenic oil, about to 10 wt. percent of solvent extract and about 15 to 3 Wt. percent of propane precipitated resin. Preferred proportions are 70 to 80 wt. percent of naphthenic oil, 20 to 15 wt. percent of solvent extract oil and 3 to 10 wt. percent of propane precipitated resins, all of said Weight percentages being based upon the total amount of base oil. The base oil composition will have a viscosity of to 100, preferably to SUS at 210 F., and a V1. (Dean and Davis viscosity index) of 10 to 70, preferably '30 to 60.

The naphthenic lubricating oil used above is a neutral distillate oil prepared from'a naphthenic crude oil. It will have a viscosity of 50 to 'SUS at 210 F., and a V.I. of 30 to 60. A commercial. oil of this type used in several of the examples is available under the trade-name of Biol a naphthenic distillate, a solvent extract from a paraffinic or a mixed base lubricating oil, and a viscous propane extracted resin, the resulting lubricant is improved with regard to water resistance (including both water. repellancy and structural stability when water is worked into the product), fire resistance and is more transparent. In addition, the lubricants have a fibrous structure and improved adhesiveness to metal. These improved properties are quite important from a commercial standpoint. Thus, certain semi-fluid versions of the mixed-salt thickened lubricants are commercially used in forced feed lubricating systems. In many such systems the lubricant flows upward through a sight glass containing water and glycerine. In this manner, the rate of lubricant flow can be 1 these properties further extend theusefulness of the grease into applications, such as automotive chassis lubrication,

where the need for these properties is obviousn'Fire resistance is also important in certain applications such as lubricant of ladle cars in steel mills where high temperatures are encountered. And of course, for a general purpose lubricant, all of the above qualities are desirable.

Surprisingly, it has been found that the above noted properties are not all obtained by using any combination of any two of the three base stock materials noted above. For example, the naphthenic distillate with the propane extracted resins actually increases the water absorption ability of the lubricant rather than decreases it. This is somewhat surprising since propane precipitated resins have been generally thought of as water-proofing agents. Combinations of the naphthenic distillate with the solvent extractin. grease, .While improving the fiber andv adhesive qualities of the lubricant, result in such a low viscosity in- The solvent extract will have a viscosity of to SUS at 210 F., and a VI. of below 0, e.g. 100 to 0. It can be prepared by solvent extraction ofpar'atiinic or mixed base lubricating oil with phenol, furfural, nitrobenzene, etc. as is known in the art. A commercial oil of this type used in several of the examples is commercially available under the trade-name of Nuso 125. a

The propane precipitated resin will have a viscosity of 1,000 to 10,000, preferably 1,500 to 3,000 SUS at 210 F., and a VI. of 100 to 150. These resins are obtained by treating a non-asphaltic crude oil, e.g. Pennsylvania or Mid-Continent crude, with liquid propane and then recovering the precipitated resins.

The above types of oils and resins are-well known in the art and the exact method of their manufacture forms no part of this invention. Rather they are described herein only to the extent necessary to identify the oils contemplated by the invention.

The lubricating compositions of the invention comprise a major amount of the lubricating base oil described above and about 5 to 30, e.g. 8 to 20-wt. percent of the mixed salt-thickener. This thickener, in turn, comprises a co-neutralized mixture of the alkaline earth metal salts of a low molecular weight acid such as acetic acid and C to C fatty acids. Usually about 4 to 20, preferably 4 to 12 moles of low molecular weight acid, e.g. acetic acid, per mole of C to C fatty acid will be used." There may also be present about 0.1 to 3.0 mole of a C to C fatty. acid or hydroxy fatty acid such asl2-hydroxy stearic aci per mole of the C to C fatty acid.

The co-neutralization is carried outby reacting an alkaline earth metal base such as the hydroxides or as the low molecular weight acid, its anhydride may be used instead. e

The intermediate molecular weight fatty acids, i.e. the C to C acids, will include those straight chain,

saturated acids such as capric, caprylic, pelargonic acid,

lauric acid, etc.

As mentioned above C to C fatty acids may also be used, such as stearic, l2-hydroxystearic, oleic, ta1low,-hy-

drogenated fish oil acids, etc.

If desired, various inorganic acids may be used to replace part or all of the acetic acid component in the preparation of the thickener. Thus, strong mineral acids such as .hydrochloric acid, nitric acid, sulfuric acid, orthophosphoric acid and spent acids from sulfonation" process spear s71 acid wherein the alkyl groups contain 3 to 10 carbon atoms can be used to advantage. An especially preferred inorganic acid is orthophosphoric acid, which is economi- 4 homogenizer or a Charlotte millji'ollowed by subsequent cooling to room temperatures if desired, grease concentrates can be made by the above techniques and then.

diluted with additional lubricating oil to form the final cal, and less corrosive to the manufacturing equipment 5 composition. than acetic acid. Furthermore, by using the phosphoric. The inventionwill be further understood by the followacid to replace a portion ottthe low mol: wt. fatty'ac'id, ing examples: the resulting grease is mademore resistant to color and. QQ E M oxidation degradation thanif no phosphoric'acidrwas *pa g used. This acid is not-volatilized during the heating proc- Grease A A base oil was prepared by simple mixing ess. Also various inorganic salts such as alkaline'earth 36.7.parts of DiolSS; anaphthenic neutral distillate lubrimetahor alkali metal: (e.g. sodium andlithiumlnitrites, eating oil having a viscosity 01555v SUS at 210 F., and phosphates, chromates and carbonates may be added to a Vl. of 35; 29.2 parts of Nuso 125, a lubricating oil thelubricant. having a viscosityot 160-SUS at-2-l-0 R, and a V.I. of Various otheradditives may also be.added to the lubri- 1 below0 prepared by phenol extraction ofnaphthenic cating composition (etg. 0.1 to 10.0 weightperce'nt based type mineral oil; and: 7.4 parts of Pennzoil resin, aresin on the total weight of the. composition), forexample, obtained-by-propaneextraction-ofaMid-Continentcrude. oxidation-inhibitors such as.phenyl-alpha naphthylamine; This resinhad a viscosityat-ZIOF. of 2,600 SUS and corrosion inhibitors, such assorbitan monooleate; supplea v.1. 0f over.. l00.. The resulting base oil had a vismental grease thickeners such as polyethyleneand. poly- 'cosity ab 210?- F of' .7 l-- SUS and a- V.I. of: 45. propylene; stabilizers suchas, aluminumhydroxy-stearate, The above base oil and=9'.2 parts of hydratedlimewere and the like. added to a fire heated kettle and intimately mixed To The compositions of theinventionmay beprepared in this slurry was added-11-.0 parts of, glacial acetic acidand several ways. In one method, all the acids. are dispersed 5.5 parts of WecolineAAC acids (a commercialacid dein the base oiland neutralizedwith themetal base. The rived from coconut oil and consisting. of about. 26 wt. resulting product can then be heated to about 225 to percent lauric acid; about 28 wt. percent caprylic acid 400 .F., preferably 250 to 350 Fa, to. dehydratev the and about 46 wt. percent capric acid); mixture. The-resulting compositionwillbe the form The mixture was stirredfo'r a halfhourand then heatof aphysicalimixtureof.thesalts. This technique is ading was begun. The heat was turned ofi' after. heating vant ageously used in making semi-fluids or soft greases-.- 30 about 0.1 hour ata temperature of.440- F. The grease It the same. composition is heated above. 400 F., say was cooled to 200F. andl partof phenyl a.-naphthylabout.430- to. 600-F., a pronounced thickening effect amine was addedasan oxidationinhibitor. The product occurs: This. high temperature. technique. is used to adwastheri Gaulin homogenized at.3,000 p.s.i. vantagewhen a more. solid. or, ajharder product is. de- Grease B .-A greasewas preparedin the same manner sired." Stilfa'nothertechnique formsja, solid or, harder as grease A, except that:the baseoiltconsistedof: 36.7 grease but avoidsthe.hightemperatures. This lasttechparts. of the naphthenic distillate andv 36.6 parts of the ni'que involves partially neutralizing the acids dispersed phen'ol extract, the naphthenic distillate andphenol ex.- q s -C- z ng 0 119 81% of:the available tract being the samepils described in grease A. acidity, heating at 300 to 350? F. for l to -8 hou rs, during Grease C.This grease wasprepared in. the same which heating theacidity further decreases to about 0.5 40 manner. as greases .A andB, except that the basefloilcon to 5.0% calculated as oleic acid of the original available sisted of 63.8 partsof naphthenic distillate oil and 9,5 acidity, and: then adding more metalbase'suificientjto parts of the propane precipitated resin. The naphthenic attaina slight degree of alkalinity. In each of the ahove distillate oil and the resin were the. same, used in preparing cases,-the mixture may then be, nextcooled toabout 200 7 grease A. to210".F., where conventional additives, if any, may be. Grease D.A fourth grease Wasprepared'in thesame. added. The grease is then cooled to below 150 where manner asgreases A, B. and C, except that the base oil I it maybe homogenized,- as by passing through a Gaulin. wasnaphthenic distillate alone.

' Table 1 H l GREASE A. is I O D I Oompon entslweight percent): A

- laeial acetic acld 11.0 11.0 11.0; Wecoline AAC acids 5.5.- 5.5-. 5.5. Hydrated lime 9.2. 9.2. 9.2. Phenyla-naphthylamine 1.0 1.0 1.0; Naphthenic oil, SUS at 210 F 36.7 63.8 73.3 Phenolext'ract oiLl 36.6-- HighVI propane extracted resin 9.5 Properties: r

Appearance Very fibrous, uniform-.. Uniform, not fibrous Uniform, not fibrous. Dropplngpoint 50 500+ I 500+ 500+.

Penetration -77! F. mum/10: Y r 'Unworkedn; 215 26 250 265, Worked strokes 3 322 v230 310.. Worked 10,000 strokes (fine hole worker plate) 377 3401. Shell roller test (4 hours):

Micro Pen. mmJlO, before 144 166 163, MlcroPen. 111111.110, after' 200 210, ballwearscanrnm. (1800, r.p.m., 10kg1load,

7 0 C, 1 h i 0.33--- 0.41 0.39. Water washing test (laboratory) (l) 'Water absorption test, percent absorbed (Mjl- 45 90.

(St-16908). Almen'test (wgtscarrled): a

Gradual loading 15 15, r Pin condition Ewell? FXPPUPW Excellent.

Shock lnadin 15 15,"

Pln conditi0n Excellent Excellent Excellent Adheslveness to metalsurfacemu uu. 0 Good Poor. wa ter wgshingqfi tleam otwaterunder pres: Noneremoyed None removed.. Turns llghtbrown Good sure.) 1i f andwashesofi.

As seen from the above examples, the combination of the base oils of the invention (grease A) resulted in a water absorption of 45 wt. percent as compared to absorptions of 90 to 115% for greases B to D. Water absorption up to about 50% wt. percent is desirable since it allows the grease to operate under damp conditions and prevents rusting and still does not adversely affect the grease. However, large amounts of water absorption, e.g. 90 to 115 wt. percent, excessively soften the grease so that it loses its structure and is easily removed from the bearings. It is also to be noted that grease prepared without the extracted oil (greases C and D) did not have a fibrous structure, which is a disadvantage in many instances due to lack of adhesiveness to metal surfaces and lack of ability to seal out water and dirt.

To further illustrate the invention a series of semifluid lubricants were prepared:

EXAMPLE II (All parts by weight) Lubricant A.A base oil was prepared by mixing 51.2 parts of Diol 55, a naphthenic neutral distillate lubricating oil having a viscosity of 55 SUS at 210 F., and a V.I. of 35; 13.0 parts of Nuso 125, the extract having a viscosity of 160 SUS at 210 F., and a V.I. of below prepared by phenol extraction of naphthenic type mineral oil; and 4.2 parts of a resin obtained by a propane extraction of a Mid- Continent crude. The resin had a viscosity-at 210 F. of 2,600 SUS and a V.I. of over 100. The resultant base oil had a viscosity at 210 F. of 78 SUS and a V.I. of 45.

To the above base oil, in a steam heated kettle, was slowly added 10.6 parts of hydrated lime while stirring. Then a mixture of 16.0 parts of glacial acetic acid and 3.8 parts of Wecoline AAC acid was added to the kettle while stirring. The temperature was then raised to about 160 to 180 F., and a free acidity determination showed the free acidity to be 3.20 wt. percent calculated in terms of oleic acid. Additional lime was then added in order to neutralize the free acidity and give a product having 0.10 wt. percent free alkalinity calculated as NaOH. The temperature was then raised to 320 F., at which point heating was discontinued and cooling water was passed through the kettle jacket. On cooling to 200 F., 0.4 part of phenyl u-naphthylamine was added as an oxidation inhibitor. The composition was then allowed to cool to 100 R, where it was diluted with an equal amount of the oil blend described above and the final composition was then passed twice through a Charlotte mill having 0.004 clearance. The

product was finished by adjusting the oil content to give a Table 2 Lubricant A Lubricant B Base formulation (percent weight):

Glacial acetic acid Wecoline AAC fif'ifl Hydrated lime Phenyl a-naphthylamrne. 131018 Diol 55 Nuso 125 (phenol extract) Pennzoil resins (2,600 SUS at 210F l 5 Properties:

Table 2Continued' Lubricant A Lubricant 13 Appearance Uniform, appears transparent.

. No great thixotropy. Suliated ash, percent i 09 4-hour centrifuge test: 1500 r.p.m.percent sedimerit.

SSU vis./100F SSU vis./210F Filtration through 100 mesh screen.

4 ball wear test--scar dia. mm., (1,800 r.p.m., 10 kg., 75 0., 1 hour).

Lubricator lite in days Sight-glass iIuid 50% water/50% glycerine, 1 (rt/day rate through dispenser.

Opaque, thixotropic but fluid.

Excellent.

+--.L 35. Sight glass fluid Fluid in sight clear. glass displaced.

1 Manzell lubricator.

As part of the above comparison, lubricant A gave a uniform transparent lubricant having a sight-glass life of over 90 days, while lubricant B gave an opaque, thixotropic material having a sight-glass life of 35 days. This sightglass test was carried out by recycling 2 gals. of the lubricant through a sight-glass containing a 50/50 mixture of water and glycerine, at the rate of 1 qt. of lubricant per day. With lubricant A, the sight-glass fluid was perfectly clear after 90 days at which point the test was discontinued. However, with lubricant B, the sight-glass began fogging after 18 days and at the end of 35 days it was no longer possible to observe the flow of lubricant through the sight-glass.

What is claimed is:

1. A lubricating composition comprising a base oil and about 5 to 30 wt. percent of a mixed-salt thickener, said thickener comprising about 4 to 20 moles of calcium acetate per mole of calcium salt of a C7 to C fatty acid, said base oil consisting esesntially of 60 to 80 wt. percent of a naphthenic oil having a viscosity of 50 to 80 SUS at 210 F. and a V.I. of 30 to 60, about 30 to 10 wt. percent of a solvent extract having a viscosity of to SUS at 210 F. and a V.I. of 100 to 0 and 15 to 3 wt. percent 7 of propane precipitated resin having a viscosity of 1,000 to 10,000 SUSat 210 F. and a V.I. of 100 to 150.

2. A lubricating oil composition containing a base oil and about 8 to 20 wt. percent of a mixed-salt thickener, said thickener comprising a co-neutralized mixture of calcium salts of acetic acid and calcium salts of a C to C fatty acid in a molar proportion of about 4 to 12 moles of acetic acid per mole of said O, to C fatty acid, said base oil consisting essentially of 70 to 80 wt. percent of naphthenic oil having a viscosity of 50 to 80 SUS at 210 F. and a V.I. of 30 to 60, about 20 to 15 wt. percent of solvent extract having a viscosity of 100 to 175 SUS at 210 F. and a V.I. of 100 to 0 and 3 to 10 Wt. percent of propane precipitated resin having a viscosity of 1500 to 3,000 SUS at 210 F. and a V.I. of 100 to 150, said base oil having a viscosity of 45 to 100 SUS at 210 F. and a V.I. of 10 to 70.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A LUBRICATING COMPOSITION COMPRISING A BASE OIL AND ABOUT 5 TO 30 WT. PERCENT OF A MIXED-SALT THICKENER, SAID THICKNER COMPRISING ABOUT 4 TO 20 MOLES OF CALCIUM ACETATE PER MOLE OF CALCIUM SALT OF A C7 TOC12 FATTY ACID, SAID BASE OIL CONSISTING ESSENTIALLY OF 60 TO 80 WT. PERCENT OF A NAPHTHENIC OIL HAVING A VISCOSITY OF 50 TO 80 SUS AT 210* F. AND A V.I. OF 30 TO 60, ABOUT 30 TO 10 WT. PERCENT OF A SOLVENT EXTRACT HAVING A VISCOSITY OF 100 TO 175 SUS AT 210* F. AND A V.I. OF-100 TO 0 AND 15 TO 3 WT. PERCENT OF PROPANE PRECIPITATED RESIN HAVING A VISCOSITY OF 1,000 TO 10,000 SUS AT 210* F. AND A V.I. OF 100 TO
 150. 